Abstract

We report on the development of highly efficient organic light-emitting diodes(OLEDs) utilized by balancing the energy transfer between multiple dopants, that is, multiple emissions from the multiple dopants were realized by balanced distributed energy transfer. From the cosensitizing fluorescent OLEDs, the peak external quantum efficiency (EQE) of 4.8% at is demonstrated, which realized theoretical limits of and means that nearly 100% of the singlet excitons are radiative. Also, the optimized device accompanying thickness-modulated electron transport layer for the enhanced light outcoupling demonstrated the highly improved peak EQE and current efficiency of 6.7%, and 23.4 cd/A.

Received 19 August 2009Accepted 11 September 2009Published online 09 October 2009

Acknowledgments:

This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea Ministry of Education, Science and Technology (MEST) (Grant No. R11-2007-045-01003-0), and partially supported by the Class University (WCU, Grant No. R32-2008-000-10082-0) Project of the MEST. And this work was partly supported by the IT R&D program of MKE/IITA (Grant No. 2009-F-017-01, Development of Fundamental Technologies for Flexible Combined-Function Organic Electronic Device) and (Grant No. 2009-F-016-01, Development of Eco-Emotional OLED Flat-Panel Lighting).

16.See EPAPS supplementary material at http://dx.doi.org/10.1063/1.3243689 for clarity of multiple emission of multiple dopants in graded configuration, the photoluminescence time resolved emission spectroscopy (TRES) of codoped thin films is performed. The Fig. s-1 in supplemental shows the TRES spectra which is the direct evidence of energy transfer, and it supports the explanations.[Supplementary Material]

Abstract

We report on the development of highly efficient organic light-emitting diodes(OLEDs) utilized by balancing the energy transfer between multiple dopants, that is, multiple emissions from the multiple dopants were realized by balanced distributed energy transfer. From the cosensitizing fluorescent OLEDs, the peak external quantum efficiency (EQE) of 4.8% at is demonstrated, which realized theoretical limits of and means that nearly 100% of the singlet excitons are radiative. Also, the optimized device accompanying thickness-modulated electron transport layer for the enhanced light outcoupling demonstrated the highly improved peak EQE and current efficiency of 6.7%, and 23.4 cd/A.